Flame sensors keep failing

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  #1  
Old 03-23-19, 04:27 AM
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Flame sensors keep failing

I have a peerless purefire 110k boiler for my cast iron radiator + indirect dhw house. Since it was installed in 2011 it has gone through a lot of flame sensors. Recently, two sensors fail per year. Sensors come out a little white so looks like lean mix to me but not sure.

I've had two techs look at it in the few years. They say the fuel mix is good. One changed the pvc outside to avoid recirc, but that didn't help. Otherwise they say everything looks good, install is good.
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Any thoughts? These sensors aren't cheap, and tired of having to worry about the boiler locking up. Thanks.
 
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Old 03-23-19, 07:58 AM
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Natural gas..... propane ?

Flame sensors are nothing more than a stainless steel rod with a wire attached to it. It doesn't "sense" anything. It only creates the bridge between the control module thru the flame to ground. They can be cleaned with a green Scotchbrite pad. Your flame may be a little lean. Have you had the burner checked ?
 
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Old 03-24-19, 07:02 AM
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Usually the CAD cell flame detectors last a few years. Here is one for $4.88
https://www.patriot-supply.com/produ...fm/CROWN_45610

It is good practice to lower burner tube temperature with a burner head protector.
See links:
HVAC Accessories, Waterglass | Lynn Manufacturing

https://www.bing.com/search?q=Oil+Bu...5fdaab13fa5644
 
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Old 03-24-19, 10:06 AM
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Did I miss something.
I looked the boiler up and it says propane or natural gas. No mention of oil fired.
 
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Old 03-24-19, 10:36 AM
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PJ,
You did not miss a thing. It is not an oil boiler and the sensors are not the cad cell that is referred to and oil does not have PVC exhaust as was mentioned by OP. Doughness' post is completely irrelevant on this thread. He must have misunderstood the post.
 
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Old 03-24-19, 11:09 AM
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Check combustion and for proper placement of the flame rod.
Combustion is NOT checked via visual inspection. It is done via an electronic combustion test meter.
 
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Old 03-24-19, 06:48 PM
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Both contractors have used combustion testers, and one made the mix a little richer than spec to see if that would solve the problem. It didn't. Any other ideas? Maybe a bad gas valve?
 
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Old 03-24-19, 06:59 PM
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Spott, when you suggest adjusting the sensor position, first, these are bolted into the cast Al front of the boiler, and aren't made to be adjusted. I could bend them, but bc they work for a couple months maybe bend away from the burner, with the idea that the burner is cooking the sensor?

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Old 03-24-19, 07:16 PM
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Can you post the results of the combustion test?
I wouldn’t modify the location of the flame rod. The manufacturer put it there for a reason.
Has anyone contacted tech support?
 
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Old 03-25-19, 06:58 AM
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Have no idea where you got the sensor relocation idea but it wasn't from me and as roughneck77 pointed out and I agree the manufacturer put it there for a reason and shouldn't be relocated IMO. If a tech cannot find the problem I would suggest calling Peerless and see if there has been a problem or they may have a solution.
 
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